Allopurinol

About Allopurinol

Allopurinol blocks xanthine oxidase, the enzyme that makes uric acid. The current Zyloprim label covers adults with gout (attacks, tophi, joint damage, uric acid stones or kidney disease), adults and children with leukemia, lymphoma or solid tumors whose cancer treatment raises uric acid, and adults with recurrent calcium oxalate stones whose urine uric acid stays above set limits despite changes in diet and fluids; it is not recommended for high uric acid without symptoms. Before gout treatment, uric acid, a blood count, a chemistry panel, liver tests and kidney function are checked. Gout treatment starts at 100 mg a day and rises by 100 mg each week until uric acid is 6 mg/dL or less, to no more than 800 mg a day, with doses above 300 mg divided; reduced kidney function means a lower start, 50 mg daily or less often. For cancer treatment, adults take 300 to 800 mg a day, starting 24 to 48 hours before chemotherapy, and children are dosed by body size.

There is no boxed warning; anyone who has had a hypersensitivity reaction to allopurinol must not take it. Serious and sometimes fatal skin reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis and DRESS) have been reported, so it is stopped permanently at the first rash or other sign of an allergic reaction. The label says carriers of the HLA-B*58:01 gene variant are at higher risk of allopurinol hypersensitivity syndrome, that the variant is more frequent in people of African, Asian (such as Han Chinese, Korean and Thai) and Native Hawaiian or Pacific Islander ancestry, and that allopurinol is not recommended for carriers unless the benefits clearly outweigh the risks. It advises considering screening before treatment in populations where the variant is common, and says screening is generally not recommended where it is rare or for current users, since the risk is largely confined to the first few months; reactions also occur without the variant. Kidney injury, reversible liver injury, bone marrow suppression, and drowsiness or dizziness are further warnings. The most common side effects are nausea, diarrhea and raised liver tests.

Gout flares can increase in the first months, even as uric acid falls, so the label recommends colchicine or an anti-inflammatory alongside it to prevent them, and says to keep taking allopurinol through a flare. Thiazide diuretics in people with reduced kidney function, and bendamustine, ampicillin or amoxicillin, raise the risk of rash. The label says allopurinol may cause fetal harm, based on animal findings, and advises against breastfeeding during treatment and for one week after the last dose. Allopurinol sodium injection (Aloprim and generics) is a separate product given by vein to people on cancer treatment who cannot take tablets.

Taking Allopurinol

How to take it

Once a day, or in divided doses above 300 mg, preferably after a meal to lessen stomach upset. Drink plenty of fluid; MedlinePlus suggests at least eight 8-ounce cups of water or other liquids a day unless the doctor says otherwise. Keep taking it, with any flare-prevention medicine, even if a flare occurs.

If you miss a dose

Take it as soon as you remember, unless it is almost time for the next dose; then skip the missed dose. Do not double the next dose.

Storage

At room temperature in a dry place, away from excess heat and moisture (not in the bathroom), out of reach of children.

Interactions to know about

At 300 to 600 mg a day of allopurinol, azathioprine and mercaptopurine doses are cut to about one third to one fourth. It is avoided with capecitabine and fluorouracil and is not used with pegloticase; warfarin needs frequent INR checks, and theophylline, cyclosporine and chlorpropamide need monitoring. Thiazide diuretics, ampicillin, amoxicillin and bendamustine raise the risk of rash.

This summarizes the official prescribing information. Your prescriber’s and pharmacist’s instructions, and the leaflet that comes with your medicine, take priority.

Why the cash price for Allopurinol differs from pharmacy to pharmacy

Generic 100 and 300 mg tablets come from many makers, so quotes for the same prescription differ by each pharmacy’s fee and markup and by whether allopurinol is on its flat-price generic list. The 200 mg tablet has fewer makers, and a prescription that names Zyloprim and blocks substitution is filled with the brand.

The dose is raised step by step, so the strength and tablet count change over the first weeks, and each new prescription is quoted as written.

Ways to pay less for Allopurinol without insurance

• Ask whether allopurinol is on the pharmacy’s flat-price generic list, and compare more than one pharmacy.
• When your dose is settled, ask the prescriber whether it can be written with fewer tablets a day, such as one 300 mg tablet instead of three 100 mg tablets.
• Once the dose is stable, ask about a ninety-day supply.
• If the prescription names Zyloprim, ask whether it allows a generic to be dispensed.
• Upload the prescription to Script Unlock so licensed pharmacies can quote their cash price. You pay the pharmacy directly.

Questions to ask your pharmacist about Allopurinol

1. 1.Should I take it after a meal, and how much fluid should I drink each day?
2. 2.What should I do if I get a gout flare after starting it?
3. 3.Which rash or other symptoms mean I should stop it and get help?
4. 4.Do any of my medicines, such as azathioprine, a water pill or warfarin, interact with it?

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